1. Field of the Invention
The subject invention relates generally to lithographic printing presses and more particularly to an apparatus and method for systematically engaging and disengaging the drive gear of a dampener with the gear train of a printing press and engaging and disengaging the dampener with a plate cylinder in the printing press.
2. Background of the Related Art
On a printing press utilizing the off-set lithographic method of printing there is typically required a dampener for applying dampening solution to a printing plate for ensuring that the non-image area of the plate, and consequently the non-image area of the printed sheet, is kept clear of ink. The dampener requires an actuation mechanism for moving it toward the printing plate to engage the dampener rollers with the plate, thereby enabling the application of dampening solution to the plate, and for moving the dampener away from the printing plate when it is not required for printing. Typically, pneumatic cylinders are employed in the actuation mechanism to engage and disengage the dampener with the printing plate.
An example of a dampener used on a printing press which may utilize an actuation mechanism as described above is that disclosed in U.S. Pat. No. 4,455,938 (the '938 patent) to J. Loudon entitled DAMPENING APPARATUS FOR LITHOGRAPHIC PRESS, the disclosure of which is incorporated by reference. The apparatus described in the '938 patent essentially includes a form roller, a metering roller, and a set of side frames for supporting the rollers. The form roller engages the printing plate for dampening. The rollers are rotated by a gear train of the printing press at a predetermined rotational velocity ratio.
Dampeners may also include a mechanism for engaging and disengaging the printing press gear train from the dampener rollers. This permits the press operator to rotate the printing press cylinders and rollers without rotating the dampener rollers. Among the benefits are reduced component wear and reduced need for maintenance to the dampener. An example of a gear disengaging mechanism for a dampener is disclosed in U.S. Pat. No. 5,551,338 (the '338 patent) to R. Wall et al entitled DRIVE DISENGAGING DEVICE FOR AN OFFSET LITHOGRAPHIC SEAL-TYPE DAMPENING SYSTEM, the disclosure of which is incorporated by reference. A disadvantage of the apparatus described in the '338 patent is it must be manually engaged or disengaged by the press operator, thereby adding additional steps to the printing process. Also, the operator must physically go to each printing head of a multi-head press, as described herein below, to engage or disengage the gear drive before each printing operation. In addition, because the apparatus of the '338 patent does not function in cooperation with existing automated printing functions on the printing press, it is possible, for example, that the operator will engage the dampener while the printing press cylinders and rollers are rotating. Doing so will subject the gear train and dampener to destructive shock loads.
To more fully appreciate the advancement in the art provided by the invention disclosed herein below it is important to note that printing presses very often include several printing heads. A large `multi-head` press can be, for example, well over 30 feet long. Each printing head incorporates the same basic components necessary to print one color of ink, namely, an inking system, a dampener, a blanket cylinder, and a plate cylinder onto which the printing plate is attached. The choice of which printing head(s) to activate for the printing operation is dependent on the number of colors needed and the type of job on the press. It is therefore economical for the operator to have the ability to remotely control the operation of each printing head component such as, for example, the dampener via the dampener actuation mechanism and the gear drive actuation mechanism disclosed and claimed herein below.